PROGRESSIVE ADDITION LENS AND METHOD FOR DESIGNING PROGRESSIVE ADDITION LENS
There is provided a progressive addition lens, including: a distance portion and a near portion; an object side surface including a first toric surface element; and an eyeball side surface including a second toric surface element that cancels the first toric surface element, wherein the first toric surface element is the element in which a vertical surface power OVPf 1 at a distance reference point which is previously defined in the distance portion on the object side surface, is larger than a horizontal surface power OHPf 1 at the distance reference point, and OVPf 1 is not less than a vertical surface power OVPn 1 at a near reference point which is previously defined in the near potion on the object side surface.
1 . A progressive addition lens, comprising:
a distance portion and a near portion;
an object side surface including a first toric surface element; and
an eyeball side surface including a second toric surface element that cancels the first toric surface element,
wherein the first toric surface element is the element in which a vertical surface power OVPf 1 at a distance reference point which is previously defined in the distance portion on the object side surface, is larger than a horizontal surface power OHPf 1 at the distance reference point, and OVPf 1 is larger than a vertical surface power OVPn 1 at a near reference point which is previously defined in the near potion on the object side surface.
2 . The progressive addition lens according to claim 1 , wherein the first toric surface element is the element in which OVPn 1 is larger than horizontal surface power OHPn 1 at the near reference point.
3 . The progressive addition lens according to claim 2 , wherein regarding the second toric surface element, vertical surface power IVPf 1 at a point corresponding to the distance reference point on the eyeball-side surface, horizontal surface power IHPf 1 at a point corresponding to the distance reference point, vertical surface power IVPn 1 at a point corresponding to the near reference point on the eyeball-side surface, and horizontal surface power IHPn 1 corresponding to the near reference point, and OVPf 1 , OHPf 1 , OVPn 1 , and OHPn 1 , satisfy the following conditions.
IVPf 1 −IHPf 1 =OVPf 1 −OHPf 1
IVPn 1 −IHPn 1 =OVPn 1 −OHPn 1
wherein astigmatic prescription is not included, and IVPf 1 , IHPf 1 , IVPn 1 , and IHPn 1 are absolute values.
4 . The progressive addition lens according to claim 1 , wherein the object-side surface includes a toric surface, in which a vertical surface power is larger than a horizontal surface power, and a difference between the vertical surface power and the horizontal surface power is constant.
5 . A method for designing a progressive addition lens comprising a distance portion and a near portion, the method comprising:
designing an object-side surface so as to include a first toric surface element and
designing an eyeball-side surface so as to include a second toric surface element that cancels the first toric surface element,
wherein the first toric surface element is the element in which a vertical surface power OVPf 1 at a distance reference point which is previously defined in the distance portion on the object side surface, is larger than a horizontal surface power OHPf 1 at the distance reference point, and OVPf 1 is larger than a vertical surface power OVPn 1 at a near reference point which is previously defined in the near potion on the object side surface.
6 . The progressive addition lens according to claim 2 , wherein the object-side surface includes a toric surface, in which a vertical surface power is larger than a horizontal surface power, and a difference between the vertical surface power and the horizontal surface power is constant.
7 . The progressive addition lens according to claim 3 , wherein the object-side surface includes a toric surface, in which a vertical surface power is larger than a horizontal surface power, and a difference between the vertical surface power and the horizontal surface power is constant.